Oxygen Levels in Oceans Are Dropping Dangerously

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Imagine if every living species in all of North America – including humans – were suffocating and unable to breathe because oxygen levels had suddenly and precipitously dropped. Every leader, from mayors to governors, would panic. And then they'd do something, anything, to deal with the clear and present danger.
That precise scenario is now playing out in the world's oceans, according to a massive, unprecedented research effort published Jan. 5 – the first truly global snapshot of depleted oxygen zones in oceans. And yet, virtually no one at any level of government seems remotely concerned. 

The study, published in Science, is a first of its kind – a comprehensive look at how "dead zones" have increased fourfold, and "low-oxygen zones" tenfold, since the 1950s. These areas now cover more than 12 million square miles of ocean and extend as much as 200 meters below sea level – an area that is larger than North America or Africa. Much of it is being driven by climate change and industrial pollution.
"If you can't breathe, nothing else matters. That pretty much describes it," said the study's lead author, Denise Breitburg, who is a marine ecologist at the Smithsonian Environmental Research Center. "As seas are losing oxygen, those areas are no longer habitable by many organisms," she told the Associated Press.
The study was conducted as part of the UN's Global Ocean Oxygen Network, and another member of the multi-disciplinary research team was more direct. "The low oxygen problem is the biggest unknown climate change consequence out there," said co-author Lisa Levin, a biological oceanography professor at the Scripps Institution of Oceanography.
Besides suffocating species living in the world's oceans in and around these low-oxygen zones, the rapidly changing ocean landscape is likely creating complex after-effects everywhere on Earth – not just in the oceans. To put it plainly: The ocean's "web of life" is certainly being harmed, but so will species on land as well at some point in the not-so-distant future. 
Oxygen is every bit as critical to life in the oceans as it is to human beings and species living on land. But while humans certainly notice when smog or air pollution creates suffocating conditions in major cities like Los Angeles or Beijing – and raise alarms to their leaders, forcing them to clean up the air – hardly anyone is on hand to observe species suffocating or struggling with similar oxygen depletion in oceans.
The ocean oxygen-depletion study, however, was largely overshadowed by a second study on coral reefs that was also published at the same time in Science. While the study of dying coral reefs is important – and a vivid, visual reminder of the impacts that climate change and warmer oceans are having on living ecosystems in the oceans - it pales in comparison to the implications of an ocean system on Earth that is rapidly losing its ability to provide basic, life-sustaining elements for every species living in the seas.
We've known about "dead zones" from chemical runoff along coastlines for some time. They're also more easily observed by people who make their living along shorelines. But observations of low-oxygen zones out over the oceans, largely driven by climate change, have been isolated to scientific research. 

The report in Science said the two, however, might be linked – and that the picture of the ocean's overall health may be considerably more complex (and dangerous) than previously thought. Oxygen levels may be changing too fast for species to adapt, driven by multiple causes now, ranging from natural variability and industrial pollution to global warming.
The researchers concluded that there may be some short-term solutions, as species migrate to places where oxygen is more plentiful. But the long-term implications, they said, could include a collapse of entire ecosystems in the world's oceans.
"In the short term, [there could be] improvements in local fisheries, such as in cases where stocks are squeezed between the surface and elevated oxygen minimum zones. In the longer term, these conditions are unsustainable and may result in ecosystem collapses," they wrote in a summary of the research.
Regardless of the causes, one thing is clear. It's long past time for human beings to pay attention to what's happening, right now, in the world's oceans. Oxygen loss in the oceans is real, significant – and growing. And it is literally a matter of life and death, even if humans aren't watching it happen.

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